320 PERCY SLADEN TRUST EXPEDITION 



20. Enchastes scotti, n. sp. (PL 15, fig. 21). 



Head (PI. 15, fig. 22). Form etc. as described and figured for the genus; frons dull 

 dark grey, a frontal triangle is demarcated by two rows of tiny bristles. Eye-margins 

 narrow and more silvery. 



Antennae orange red. 



Face shining grey with four bristles each side pointing to the centre line and a few 

 other scattered ones; facial knob extremely shining. Jowls and back of head rather 

 silvery. Prelabrum horny, shining with silvery sides and central spot ; tongue coriace- 

 ous, the palpi are hidden. 



Thorax and scutellum blackish with a fine faintly greenish granulation and black 

 bristles. 



Wings with venation as figured with third and fourth veins convergent at the end ; 

 veins pale. 



Halters orange. 



Legs : femora and tibiae dark black-grey with orange knees and tarsi except the last 

 joint. The middle femora with stronger bristles in front. 



Abdomen shining black-grey slightly suffused with reddish at the base ; second, 

 third and fourth segments increasing progressively in breadth, fifth pointed, pollinated 

 and more hairy than the others. 



Size. Just under 3 mm. 



Locality. Seychelles. Mahe : from seaweed on beach at Anonyme Island, I. 1909. 



Discomyza, Meigen. 



Discomyza Meigen, System. Beschr., vi. (1830), p. 76. 



21. Discomyza similis, n. sp. 



This species is allied to the Palaearctic D. incurva Meigen, from which it differs in 

 many points but most markedly in the breadth relative to the length. It is about as 

 long as D. incurva but is proportionately more slender than that insect ; the ratio of 

 maximum thoracic breadth to length measured from the scutellar junction to the front 

 margin is slightly greater than lj in D. incurva,, while in the new species the ratio is 

 about unity : this ratio holds approximately also for the head and abdomen. 



The following description is based principally on the differences between D. similis 

 and D. incurva. 



Head. The frontal triangle is proportionately larger and is somewhat wrinkled or 

 rugose instead of being flat and shining. The face is similarly knobbed on each side 

 below the antennae, but just below these there are from six to eight small circular pits 

 instead of a shining triangle. Antenna black, the third joint slightly suffused with grey 

 instead of the second joint being extensively bright red, the arista is six-rayed : the 

 chaetotaxy is the same, but the bristles are longer and less stout. Correlated with the 

 greater ratio of length to breadth the face is more rounded in outline. 



